Now here’s a phrase that I never expected to write: Neville Longbottom broke the internet! More accurately, the cover image of the latest issue of Attitude magazine featuring Matthew Lewis, the actor who played the porky, pasty Harry Potter character, now looking ripped, buffed and honed to perfection, with a set of abs you could grate nutmegs on, crashed the magazine’s website yesterday.

The tighty-whitey Armani underwear hugging Lewis’s lunchbox and hanging off his newly protuberant hipbones can take its place alongside Kylie’s Agent Provocateur scanties and Kim K’s massive arse in the annals of web-wrecking clickbait. To compound matters, J K Rowling tweeted her approval of the new Nev, which felt... weird. A bit like your mum growling lasciviously at a mate you’ve known since primary school.

Welcome, gentleman, to the Mansformation, a process which can turn weedy nerds into objectified metrosexual love gods. Lewis follows in the wake of actor Chris Pratt, and musician/DJ Calvin Harris, whose lank hair, bad teeth and skinny light-blue limbs marked him out as a native Scot but who recently sculpted himself into a muscular hunk fit for both an Armani underwear shoot (there’s a theme developing here) and for the much-coveted post of Mr Taylor Swift (geeks need not apply). Then there’s small, willowy, wispy Freddie Fox, who re-contoured his body entirely, acquiring impressive lats, traps and delts — and an inguinal crease to rival David Gandy’s — to play Freddie, the object of desire to all ages and sexes, in Russell T Davies’s Channel 4 drama Cucumber.

Hot stuff: Matthew Lewis on the cover of Attitude

Harris, Lewis and Fox are following in a furrow trodden by many a Hollywood actor before. Christian Bale, Brad Pitt and Adrien Brody have dieted and exercised themselves from puny to pumped and back again according to the demands of their craft, and Jake Gyllenhaal is the latest — creepy and skinny as a parasitical video journalist in Nightcrawler, he’s now bulked up like a beast to play a boxer in Southpaw.

The difference is that the British boys aren’t A-listers. Indeed, their appeal was built on their ordinary bloke-ishness, although Fox admittedly occupies the posher, prettier end of that spectrum. But the promise that their reincarnation holds is the same made by the Charles Atlas bodybuilding ads that were such a feature of popular culture in the Seventies: Tired of being a 98lb weakling? I can turn you into a REAL man!

It should be a geek’s dearest wish — beanpole to Poldark — with the added bonus that the Mansformation is actually obtainable. If, that is, you have the time, money and gumption to stick to a punishing and joyless regime. Lewis employed a personal trainer (he is playing one in a film) who put him on a gruelling exercise regime and a diet that cut out sugar, carbs and alcohol. Harris works out with weights and does Pilates daily and exists on a diet of egg-white omelettes, spinach and the perfumed air of Swift’s affection.

Fox swam and did resistance exercises daily, ate only chicken, salmon, brown rice and sweet potato for months and cheerfully admitted that he couldn’t wait to “Disembowel the dirtiest cheeseburger I could find” on the last day of shooting. (Once, Matt Roberts, fitness trainer to the stars, assured me that he could carve a body like his out of puffy flesh like mine. I could see behind his eyes that he didn’t think there were enough days in the year.)

There is also a danger in emulating too slavishly an ideal of gay beauty that also appeals to women. I can sum this danger up in two words: Shane. Warne. During his brief tenure as Liz Hurley’s cleavage enhancer, Warne did the opposite of Lewis’s geek-to-hunk transformation, morphing from a rufty-tufty, rugged cricketer into a tweaked, tweezered, highlighted and moisturised wax effigy, the groom of Wildenstein. As with other masculine neologisms, from mansplaining to manscaping, the Mansformation should be approached with care, if not outright suspicion.